Mowee knives



-6 Sheets-Sheet l. R. BUTTON.

MAGHNE POR GRINDING MGWER KNIVES. ,964, Patented Mar. Z2, 1887.

(No Model.)

(No Model.) s sheets-sheet 2. R. BUTTON.

MACHINE FOR GRNDING MOWER KNIVES. No. 359,964. Patented Mar. 22, i887.

6 sheets-sheet s.

(No Model.)

R. BUTTON.

MACHINE POR GRINDING MOWBR KNIVES.

venor.-

Patented Mar. 22,1887.

6 Sheets-Sheet 4.

(No Modem R. BUTTON.

MACHINE FOR GRINDING MOWBB. KNIVES.

No. 359,964. Patented Mar. 22, 1887.

I/\` a ,f figli E' ,l lf' l l' f lf /l 1. 'fil/ l gl f Q v www ifffnV-w 1w Il" h- 1min nih. Q Tl l n Tl (No Model.) l 6 sneets-sheet 5.

f R. DUTTGN.

MACHINE POR GRINDING MOWBR KNIVES.

No. 359,964. Patented Mar. 22, 18877.

6 Sheets-Sheet 6.

(No Model.)

R. BUTTON.

MACHINE P011 GMNDING MOWBR KNIVES.

N0. 359,964. Patented Mar. 22, 1887..

Muy.

IINITED diurne PATENT Orsini-n GRIIIDER COMPANY, OF NEV YORK, N. Y.

MACHINE FOR GRINDING IVI(.'Mll/EFl-lhllh'ba SPECIFICATION forming part of Letters Patent No. 359,954, dated March 22, 1857.

Application filed October 1-1, 1886,

Serial No, ilfl-lS. (No model.)

To all whom it may concern:

Be it known that I, Ruuu's BUTTON, of Yonkers, in the county of NVestchester and State of New York, haveinvcnted certain new 5 and useful Improvements in Machines for Grinding Mower-Knives; and I do hereby declare that the following specification, taken in connection with the drawings furnished and forming a part thereof, is a clear, true, and xo complete description ofthe several features of my invent-ion.

illy said improvements have all been devised with special reference to their use in connection with that class of machines which were disclosed in my Letters Patent No. 842,290, dated May IS, 1886, although some of the features now disclosed have more or less value when applied to other types of mowerknife grinders.

One of the most important features of my present invention is believed to be radically new and of equal value in any mower-knife grinder wherein spring pressure is relied upon for maintaining contact between the knife and grinding-wheel during the actual grinding operation, and also wherein either the wheel or the knife-clamp is reciprocated for progressively grinding the edge of alrnife. sect-ion from the bottom to its tip.

In all prior machines the spring which controls the knife-clamp exerts greater force and causes heavier contact of the knife with the grinding-wheel while grinding the bottom of each knife-edge than while grinding the tip or upper or outer portion of the same edge, be-

cause of the fact that although the spring is compressed by the rearward deflection of the knife-clamp, as when grinding at the tip of a knife-section, the effective force of the spring 4o is greater while'grinding at the bottom of the V, which is nearer the fulcrum or pivot of the knife-clamp or its frame than the outer end or tip of the knife-edge. The application of the greatest spring-pressure while the grindingwheel is operating on the bottom of the V of a knife as heretofore is obviously bad in prin\ cipie, inasmuch as the outer portions of each edge do more work andare consequently more liable to wear than the inner portions, and 5o hence the latter will usually need less grinding, and instead of being ground under the greatest available pressure said inner portions should be ground under a pressure at least no greater than when the outer portions are being ground; or, in other words, it is highly advantageous it' the spring-pressure be practically equalized, so as to secure a uniform contact-pressure while grinding all portions of an edge; but I deem it best to have the pressure somewhat greater while grinding near 6o the tip of a knife-section than while grinding at the bottom of the V, and I have therefore for the first time so organized a knife-clampcontrolling spring with the grinding wheel frame and the clamp-frame that the spring will exert its minimum force while the grinding-wheel is in contact with the bottom of a knife-edge, and then progressively increase its force as the point of contact is gradually moved toward the tip of theknife edge orsec- 7o tion. Although I have provided for this progressively-increased pressure while grinding outward and a gradu'ftlly-decreased pressure while grinding inward on a knife-edge, my spring can be so adjusted as to enable the pressure to vary so little as to make it practically uniform.

Another feature now devised by me is specially applicable to such machines as were disclosed in my aforesaid Letters Patent, and in 8o which the grindingwheel frame and the knifeelamp frame are swiveled together and movable in the arc of a circle centering within the grinding-wheel. In said machines stops are employed for limiting the swiveling movement; and as heretofore organized by me said stops were absolute in their operation and fixed in their positions, which rendered the machines thoroughly satisfactory when used for grinding new knives, or even old knives 9o which had only been ground in my machines; but a knife having more or less irregularlyground knife-sections, as a result of their having been previously ground upon au ordinary grindstone or by means of other types of g5 grinding-machines, requires that there should be a capacity for a special adaptation to each knife-section in order to Widen the range of usefulness of said machine.

In this connection another feature of my roo invention consists in providing swivelingstops which are adjustable, so that they may be moved toward the right hand or toward the left andibe then iirmly tixedin position. Thus, while restrictingthe eXtent of the swiveling movement as between the knife-clamp frame and the wheel-frame, the same as in my prior machines, I now further provide for a variable location of said stops to enable the swiveling movement between the knifeclamp frame and the wheetframe to be correspondingly varied.

Another feature of my present invention is mainly restricted in value to use in that form of machine disclosed in my said Letters Patent, in which the grinding-wheel is mounted at vthe end of an arm pivoted upon the wheel-` frame, so as to allow the wheel to be vertically reciprocated by the hand of t-hc operator applied to a handle at the opposite end of said arm.` In my said prior machine the wheeldriving crank and the driving-gear coupled to said crank were located at andupon the pivot by which the wheelarm and wheelframe were connected, and whileK that arrangement is highly effective I havefound that some persons, while operating the crank wit-h the right hand and controlling the wheel with the` left hand, experience more or less difficulty in preventing the power applied through the crank from adversely affecting the desired control of the grinding wheel, and I have greatly remedied this by providing an independent base for the crank and its gear and meshing the latter with an intermediate gear` which is mounted upon the wheel-arm pivot, and as a further result of this change and its accompaniments the machine is rendered more compact and much lighter in weight than my prior machines of this general form.

With a view to further lessening the weight of the machine, as well as its cost, I now employ a knife-clamp embodying certain novel features andof simpler construction than those used in my prior machines, which, with the other changes now made, enable me to produce a thoroughlyeffective machine, weighingonly about two-thirds as much as machines of the same general class as heretofore produced by me.

In my prior machines a chamberedgrinding-wheel is employed for the reception of water, and I employ such wheels in my present machines; but I have now so improved them that water can be more conveniently introduced and` retained therein. In my prior wheels a feedduct and a plug were employed; but I have now provided `a duct whichlneed never be closed and which can. be provided with a mouth, by which water can be readily supplied to ,the wheel while it is in its work-` ing position and without the a-idvof a funnel or other special contrivance.

' To more particularly describe my invention I will refer to the accompanying six sheets of drawiugs,-in which- Figure 1, Sheet 1, is a side view of a simple form of :my machine embodying all of my presD ent improvements. Fig. 2 is atop view of the same. Fig. 8, Sheet 2, is a side view oppositet to that in Fig. 1. Figs. 4 and 5 are, respectively, side and top views of such portions of this machine as relate to varying the angular adjustment of the grinding-wheel and knifeclamp. Figs. 6 and 7, in two views, illustrate a plate-metal spring for controlling the knifeclamp. Fig. 8 illustrates a rubber spring fori controlling the knifeclamp. Figs. 9 and 10, Sheet 3, in two sectional views, illustrate the chambered grinding-wheel providedfwith my` Y novel water-feeding duct.

Figs. l1 and 12, in side and sectional views, illustrate the grind ing-wheel provided witlii my` feeding-duct in another form. Fig. 13, Sheet 4, is a front view of a knifeclamp detached, a `portion of a mower-knife being therein indicated in dotted lines. Fig. 14C is an end viewrof said clamp and also of thelever by` which it is in kipart controlled in its `relations tothe grinding-` wheel. Figs. l5 and 16, in frontandtop views, illustrate one pair of knifeclamping jaws in a modified form. Fig. `17, Sheet 5, in side view, illustrates a base-clamp, a knife-clamp, a-.por` tion of the wheel-frame, and the adjustable stop devices in amodiiied form. top view of the base clamp-plate and adjust-1y able stop-plate of Fig. 17 with the knife-clamp removed but having a portion of` the wheelframe shown in dotted lines. and top views, illustrates said clampplatede- Fig. 18 is a i Fig. 19, in end i tached. Fig. 20, in side `and top views, illus` f trates the plate which carries the adjustable stops detached from the clamp-plate. Fig..2l, Sheet 6, is a side view `of a complex form of my machine capable of various modes of op` eratiomand illustrating the main features of my present invention as applied thereto. Fig.

IOO

22 is a side view of a vertically-reciprocatingz knifeclamp having a bent spring arrangedto i progressively increase its force during the downward movement ofthe clamp.

Thegrinding-wheelA,asinmypriormachine, is chambered for the reception of water, which is delivered through the grinding-face as arresult of the rotation of the wheel. the plugged aperture or feed-hole heretofore used by me, I now employ a feeding-duct which requires no closing. This duct can be` somewhat variedrin its form; but it must have an entrance or mouth to allow water to dow downward andtinward and an exit within the wheel at such a point with relation to the mouth that water cannot iiow outwardly from the chamber, either when the grinding-wheel is at rest or in motion. As shown in Figs. 9 and IO, the feeding-duct is in the form of a bent tube, c, inserted tightly through la hole in one of the wheel-ilanges and extended radially a little beyond therraxis offtheiwheel.

In lieu of In Figs. 11 and 12 the duct a `is within eXterior and interior webs cast integrally with one ofthe wheel-anges. `Either form enables water to be supplied to the chamber through the open moutlin a, which of course could be plugged if anyone desired so to do;` `but it will obviously be wholly unnecessary, because in whatever position thc machine or the grindingwheel may be water cannot ilow outwardly unless it be greatly in excess of a desirable quantity. Vhen the wheel is in motion, the entire liquid contents of the chamber will of course be annular-ly distributed therein, and evenly, and hence there will be no tendency for the water to pass outwardly through a duct which occupies in the wheel aline more or less radial. f

Vith a considerable body of water within the wheel, it is sometimes delivered too freely through the grindingface, and to prevent this I use a waterguard, afi, composed of an annular band or strip of any material not freely pcrvious to water, and, while heavy cloth or ielt might serve a goed purpose, I prefer to use thin sheet metal, corrugated as shown, and laterally so occupying the chamber as to not wholly prevent water from passing toward the grindingface ol the wheel. rihis water-guard could, however, be so tightly clamped between the wlieel-iianges as to prevent water from passing at its edges; but in that case a few small perforations should be provided.

A cheap and fairly-effective water-guard may be provided in the form of an interior impervious coating to portions of the annular surface of the grinding-wheel, thus lessening the area of exposure to penetration.

Referring specially to Figs. l to 5, I will describe the wheel-framc B, which differs in some more or less important features from that of any of my prior machines; but most of said variations are incident to the presence of the more important features of my invention. As in my l prior machines, said wheel-frame is composed ol" a bracket swiveled upon a bedplate and a wheel-arm, B', pivoted upon said bracket, as at I), as in my prior machines of this general form. In said prior machines the crank b and its shaft bi were mounted upon the wheel-arm B', but now saidy crank and shaft have bearings ina rearward]y-projecting hanger, D, integral with said bracket below the wheelarm The chain of gearing from the crankshaft to the grinding-wheel is substantially as in my prior machine; but the outer bearings for the wheelshaft and the shaft of the adjacent gear are slightly differently formed, being now on a. hanger extended downward from the wheeL guard and integral with thc arm B', instead of being extended upward, as in said prior machines.

The base-clamp G, by which the machine may be securely mounted upon the wheel of a mowingmachine, as for use, differs from those previously used by me in that instead of four but three jaws are now used-two at one side,

as before, and one centrally opposite, as at c, j

on a single bolt, c', provided with the thumbnut 0". l find that the one bolt and one jaw amply serve the purpose, thus lessening the weight and the cost of that portion of the machine.

The knife-clamp frame l) is pivoted on a horizontal bolt at d to the base-plate of the machine in my prior machines; but it is now provided with apair of arms, e, slightly above the plane occupied by the pivot d, and proA jecting toward but at both sides and beneath the grinding-wheel, as clearly indicated in Figs. 1 and 2. On the base-plate below the Wheel there is a bow-shaped lever, f, pivoted at f to the baseplate, and at its two ends, fl, bearing downward upon the coincident ends of the arms e of the clamp-frame. At the bow end of the lever f there is a. hoolgj', by which one end of a contractile spiral spring, g, is attached for exibly coupling said lever f with the wheel-arm B', said spring at its upper end being Connected to a screw-threaded rod or linlr, g', which extends through a hole in said wheel-arm and is provided with a thumb-nut, g2, bearing on said arm, by means of which said spring may be adjusted to any desired tension, and to correspondingly vary the force with which the knife-clamp is normally forced toward the grindingface of the wheel. The point of vconnection between said spring and its link and the wheel-arm B is located between the pivotal point b and the grintli1ig\i-'l1ecl, and therefore, as said wheel is raised by depressing the opposite end of said arm by means of its handle h, the tension on said spring is gradually increased, so that on commencing to grind a mower-knife at the bottom of a V the spring will exercise its normal or least pressure, but as the wheel is raised for grinding upwardly toward the outer ends of the knife-sections the tension of said spring is gradually increased until its extreme pressure is developed while grinding at the outer ends or tips ofthe edges. The rear end ofthe bow-leverf at its under side ahuts upon a projecting portion of the bracket B, thus enabling the latter atf" to serve as a stop, by means of which the knife clamp Vframe is confined against undue movement rearward or away from the grinding-wheel.

The bracket-arm of the wheel-frame, as in my prior machines, has aforwardly-projecting stud below the wheel, serving as a stop, fi, by means of which and two adjacent abntinents the extent of the lateral swinging movement is restricted, and in said prior machines said abutments were tired portions of the machine; but I have now devised adjustable stops by means 0f which the angular relations of the grinding-face and a knife-edge can be varied, to provide for grinding knives which have not been previously ground with desirable uniformity. As shown in Figs. LLand 5, said stopabutments i t" are vertical studs on a dat plate, 7c, pivoted at one side, near one end, as at k', to the base-plate, and at the other end provided with a curved slot, 7c, occupied by a vertical sorewpost, k, projecting upwardly from the base-plate, and provided with a washer and athumb-nut, r, thus enabling said stops or abut-ments to be swung slightly to either side of their normal position and permitting all variations in the angular rela- IZO portions of the machine.

which could be desirable lfor operating upon mower-knives which have been im perfectly or irregularly ground prior to thc use of my ma.

chines thereon. lt will be obvious that it is immaterial in what particular manner these stops or abutments i z" are rendered adjustable, as will be hereinafter made lapparent in connection with other forms of my machine.

The `vertical pivot or bolt at E, by which the wheel-frame and knife-clamp frame are swiveled with relation to each other, is as in: certain of my prior machines, and the base-plate E is changed in form only so far as to harmonize with the several variations in other lt must not, however, be understood thatwith my present features of invention the pivot or boltE is, ofnecessity, the only direct means of connection between thewheel-frarne and the base-plate, or between-the wheel-frame and the knifeclamp frame, as will hereinafter be fully shown in connection with one form of my machine in which the plate which carries the adj ustable stop-abutments serves, also', as an intermediate com iecting-li nk between the wheel-frame and the base-plate.

The knife-clamp F (shown in Figs. 1, 2, 3, 13, and 14) differs in many respects from that shown in Fig. 21, the latter being substantially as shown in my said Letters Patent. My

present clamp has a knife-seat at Z on a hori-` zontal bar, Z, which is a portion of the clampi'rarne D, and atthe ends of-said bar there are stationary jaws Z' l, and for each of these there is a loose jaw, m m, having a bearing-point below said bar at m? for contact with a corresponding portion of the coincident stationary jaw, and eachpair ofjaws hasa threaded bolt, n, and a thumb-nut, a. The clamping-face of each `pair of jaws is at n?, between which a knife-section is clamped above the knife-bar, as clearly indicated in Fig. 13. At a nearly central point on said knife-seat there is'a vertical bolt, o, having a head which `will just overlie the edge of the knife-bar when a knife is inthe clamp, as for giinding. As inmy` prior machines, this bolt serves as a gage for` locating the dividing-line between two knifesections, although in this case it is one edge of the head that serves as a gage-point, asindicated, instead of the center, as in my `prior machines; and so, also, does this bolt, by the Contact of its head with the outer edge of a knife-bar, contribute to convenience in adjusting a knife in the clamp. For conveniently throwing the clamp rearward one of the loose jaws, m, is provided with a thumb-piece, n3. Inusing this clamp it will be seen thatthe bolt o serves to prevent a mower-knife, n, from tilting endwise andedgewise, and hence one pair of these clamping-jaws can be set so as to confine, but not tightly engage with,a a knife section, and not require any manipulation of its clamping-bolt during the grinding of all but one section of an entire moweryposed of three parts.

knife, the other pair of jaws doing nearly all the actual clamping duty.

For better enabling the clamp to thoroughly the jaws, it being obvious that the vertical bolt o serves as a clamping-face for the rear side of a knife and that it co-operates with the arm m when the latter is forced against they opposite side of a knife.

Referring now to the4k novel combinationi which includes the spring g, as shown in Flgs.`

1, 2, and 3, it is not to be understood that` said spring must be of the contractile variety, because an expansive spring may as well be em-` ployed,as illustrated in Fig.r 8, wherein the leverf has a tail-piece and a Vertical strap,f5, within which is an expansive rubber spring, g, through which the link or .rod g passes, the latter having a nut or head at its lower end and a washer intervening `between said fnut and the lower end ofthe spring. In lieu of springs of either of these Varieties, a platevspringrnaybeemployed, as illustratedin Figs.

6 and 7,wherein thebow-shaped leverf is corn- The -fpivoted portions f6 are rigid, but the rear portion is bow-shaped and has acentraltintegral:tongue-piecafl, all

composed of spring-steel plate well propor-` tioned for the duty to be performed, the tonguepiece being coupled to the link g', asbefore described.

In Figs. 17 to 20, inclusive,'Ihaveillustrated t ,portions of` one form of my machine in which the wheel-frame bracket Bi :is as `before describe-d; but the base clamp-plate, E,is `not directly swiveled to said-bracket by the pivot or bolt E. Inthis instance the plate k is pivoted `to the baseplate E by means of -the pivot-bolt at 7c', and-said plate k has at its opposite side a bearin'gvor sleeve, 765, for the reception of the pivot-bolt E'. The knife-clamp frame is pivoted upon the base-plate asin the other forms of machine, and therefore the general pivotal relations `of` the grinding-wheel and the knife-clamp are as before described, although the plate 7c serves not only as a carrier, for the stop-abutments i', but `also as an` intermediate connecting-link between the grinding-wheel ,frame and the base-plate on which the knife-clamp is mounted. This plate k, like the similar `plate before described, has a curved slot, k2, occupied bythe screw-post L3, having a washer and ,thumb-naakt, all as Vpreviously described, for enabling the adjustment of the stopsz" and .confining them in po-` sition.

The spring g is here shown in dottedi lines. 13o

withy its lower end connected to the leverf, and the latter, instead of being bow-shaped,

has but one curved arm, and its end] engages at but one point With the knife-clamp frame D, as at e, instead of at tWo points, as in the instances previously1 described.

It is now to be understood that this feature of my invention, by which progressively-increased spring-force is applied to the knifeclamp during the grinding-contact of the Wheel and knife, start-ing from the bottom of a V and grinding thence to the tip of an edge, is not restricted to those forms of my machine in which the grinding-Wheel is vertically reciprocated, as it will now be made obvious that similar results Will accrue if the spring be properly applied to a knife-clamp and frame which can be vertically reciprocated while the wheel is rotated on a nou-reciprocating arm. In the complex form of machine shown in Fig. 2l the knife-clamp is pivoted to the clampA frame D upon a supplemental frame, as at d, so that the clamp can be vertically reciprocated by means ofthe hand-lever p, as shown and described in my aforesaid Letters Patent, and, as in said prior machine, a spring, p', performs the lifting movement of the clamp-frame after it has been depressed by the hand-lever. A knife-clamp spring was also used in said prior machine; but it was seated at one end upon a cross-bar between the arms, by which the knife-clamp was pivotally coupled to the knife-clamp frame, and said spring was slightly inclined forwardly to its point of contact with thelrnife-clamp. In myimproved machine the spring gi has its rear end abutted against the side of a slotted standard, g4, and it encircles a rod, g5, (provided with an adjusting-nut, gli) so that as the knife-clamp is depressed, as for grinding a knifeedge from the bottom of a V outwardly, said spring is progressively compressed and caused to exert a gradually-increased pressure of a knifein the clamp upon the grinding-face of the wheel, and in a manner as closely approximating to the operation of the spring g before described as I believe to be possible, when said spring is not directly controlled and graduated by the movements of the wheel-armin the simpler forms of machine.

In said Fig. 2l the form of knife clamp shown is the same as that disclosed in my said Letters Patent; but the forms herein disclosed can be used in this complex form of machine,

as is illustrated in Fig. 22, wherein the spring gi is of the simple bent variety and composed of spring plate metal, secured at one end by means of a slot therein and an adjusting clamp-screw, gl, to the standard gt, which, as before described, projects upwardly from the base portion of a knifeciam p frame, and at its other end it abuts against the rear of the knife-clamp in a suitable seat, so that as the clamp is depressed the force of the spring is progressively increased in the direction of the grindingwheel and progressively lessened as the clamp rises, thus affording the same results as with the springs of the spiral form.

It will be observed that in the form of machine shown in Fig. l the knife-clamp spring is coupled to the Wheel-arm between its pivot Z1 and the wheel, and also that it has been shown that said location of the coupling-point will admit of the use of either contractile or expansive springs. It is now to be understood that said coupling-point can be located between the wheel-arm pivot and the outer end or handle of said arm Without materially impairing the results. In this complex forni of machine, Fig. 21, the knife-clamp can be locked against vertical reciprocation and the Wheelarm then unlocked, so that the grinding-Wheel can be vertically reciprocated.

It will be readily obvious that in the simple form of machine shown in Fig. l the bowshaped lever f is constructed separately from the knife-clamp arms e, simply because the force of the spring is increased by the upward movement of that portion of the Wheel-arm to which it is coupled, and hence, if said spring be coupled 'to and controlled by a portion ot' the wheel-arm which moves downward from its normal position, said arm e may be extended below and beyond the pivot I) of the Wheelarm, as shown in Fig. 21. lith the clamparms e thus extended, of course the pressure must be exerted downwardly, and hence the spring gl3 abuts at its lower end upon said clamp-arms e, (the tivo being coupled at their rear ends in bow forn1,)and its upper end abuts against the adjusting nut gg on the rod gl", which at its upper end abnts against aseat on the under side of the wheelarm and at its lower end passes freelythrough a hole in said clam p-arms e. This arrangement of the pressure-graduating spring, so far as its rod and adjusting-nut go, is the same as in the case of the spring g, before described. It will be readily obvious that in operating a complex machine like that shown in Fig. 2l both clamp-springs g and g8 could not be used at the same time, and hence either can be readily displaced or rendered inoperative; but a machine thus organized, being capable of use under all possibly-desired conditions, cannot fail to meet the varied preferences or requirements of its users.

It will also be readily seen that however the clamp-controlling spring may be operatively coupled to the knife-clam p by way ofthe wheelarm, or however varied the spring may be ICO IIS

in form, it Will operate in substantially the saine Way to press the knifeclamp toward the grinding Wheel with a gradually increased force in grinding fromV the bottom ofa V to the tip of an edge, as a result of that reciproca-ting movement by which the entire knife-edge is progressively subjected to contact with the grindingsurface of the wheel; and it will also be as readily seen that when said clamp-controlling springs are not controlled by the pivoted wheelarm (as with the springs g"Jv and g5, Figs. 2l and 22) they are also graduated in force as the result of that same reciprocatory movement effected by the hand-lever p, which is pivoted upon the Wheel-arm bracket and is vibrated vertically like the Wlieelarm in the other forms of machine, thus clearly indicating the fact that the wheel-arm B', when vibrated to progressively vary the force of the clamp-controlling spring, is no more than a hand-lever operatively coupled to said spring, and in this particular combination it is therefore the equivalent of the hand-lever p.

If the spiral springs be composed of steel, it is generally desirable to loosely house them ro for protection against undue corrosion, and to accomplish this a cup-sleeve, gu, as shown in Fig. 21 on the spring g?, can be employed with good results on any of the spiral springs.

This complex form of machine can, obviabutments mounted on a plate, as in the simpler forms of my machine; but instead of the swinging plate l have here shown simple stopscrews i", the inner ends of which serve as adjustable stops or stop-abutments, with which the wheel-frame stop t' can be made to variablylengage, and thus enable the knife-clamp and wheel to be adj usted for grinding irregularly-ground knives, although this form of adjustable stops is not deemed by me so convenient and desirable as those previously described.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. In a machine for grinding mowing-inachine knives,` the combination, substantially.

as hereinbefore described, of a knife-clamp, a grinding-wheel, means forreciprocating either of them for presenting to the grinding-surface a knife-edge progressively from the bottom of a V to the tip of an edge, and a clamp-controlling spring which exerts its minimum force during the presentation by the clamp of the inner end of a knife-edge to the grindingsurface and a greater force when presenting the outer end or tip of a knife-edge to said surfaccyand is coupled to the reciprocating mechanism and graduated in its force thereby, substantially as described, whereby the pressure of a knife held by said clamp is increased progressively against the grindingsurface while grinding from the bottom of a V tothe tip of a knifeedge.

2. In a machine for grinding mowing-maously, be provided with adjustable stops ory chine knives, the combination, substantially `face of the wheel.

force while pressing a knife against the grind.`

said arms, and a clamp-controlling spring coupled to the opposite lend of `said lever andiy j also to said wheel-arm between its pivot-and the wheel, whereby as the result of vertically moving said wheel the pressure of said spring applied at the rear of the clamp-frame is progressively increased.

4. In a mower-knite-grinding machine, the combination, substantially as hereinbefore described, ofthe grinding-wheel and the knifeclamp `pivoted with relationto each other, substantially as described, for enabling the presentation of a knife held by said clamp to i either of the edges of the face of the grindingwheel, and adjustable stops for variably limiting the pivotal movements of ;said wheel andiV clamp, and thereby correspondingly varying their angular relations for operating upon the l sections of a mower-knife which has been irregularly ground. S5

5. Inaniower-knife grinder, the knife clamp; embodying the combination, substantially as t described, of the horizontal bar provided with legs pivoted at their lower ends and having an upper surface affording alongitudinal seat for the rear edge of a knife-bar andhaving a centrally-located bolt affording a shoulder' for engaging with the outer edge of a knife-bar, and two pairs of independent vertical clamping-jaws located at opposite sides of said bolt, 95 whereby the central portion of a mower-knife' may be securely coniined by the use of either or both of said pairs of jaws, and also whereby either ofthe pairs ofjaws and said bolt-shoul` der can be relied upon for securely holding either end of a knife while grinding the end` sections thereof. y

6. The combination, substantiallyas hereinbefore described, of the grinding-wheel, the knife-clamp and its frame, the-latterbeing pivoted at its lower end to a base-plate, a horizontal bar on said frame serving as a seat for the rear edge of a mower-knife bar, a rigid clamping-jaw at cachl end of said bar, a pair f of movable jaws, each provided with a separate clamping-bolt,forwardly-projecting arms l at the base of said clamp-frame, and a spring for forcing said arms downward and thereby forcing the knife-clamp toward the grinding- IOO Vitnesses:

C. H. PINNHOUR, Jr, W. N. GAY. 

